In order to prevent the hazards of rock burst and the spontaneous fire in deep-level mine and ensure that the ventilation run safely and reliably, the variation trends and the distribution rules of the air flow in deep-level mine are analyzed. Based on the network flow theory and statistics principle, the density equations of the air quantities in the airways are established. With the maximum likelihood estimation (MLE), the rationality of the parameters in the air quantities distribution equations is verified. By means of the disjoint minimal path set algorithm, the reliability assessment models of mine ventilation network are founded. All the calculation processes are realized in the environment of MATLAB. The results indicate that the indexes of the quantitative analysis reflect the practical situation of the ventilation network in Daliuta coal mine.
Through field test, physical and mechanical properties, mechanical composition, characteristics and compaction properties of the Yellow River alluvial silt soil were analyzed. The result shows that silt inside air compaction was difficult to discharge due to the influence of soil particle composition and low content of clay. As a result, the uneven settlement deformation of subgrade is obvious and the stability of silty soil water is not enough. The rainfall is frequent. Moisture content of soil is too high. It is difficult to dry field soil. The construction period is short. In order to speed up the pace of construction, we proposed the over-wet silt optimal multiple water control technology.
Taking the Hongqi west road station construction of Dalian metro line 2 as an example, the regularities of the temperature and the smoke concentration distribution are analyzed. Basing on FDS, the simulation model of the metro station fire is set up. Assume six fire points in the station to simulate the smoke diffusion velocity and the personnel evacuation time in fire. Results show that the chimney effect is obvious at the back of the station. The highest temperature of every export is 180°C and the lowest temperature is 40°C during the effective duration. The time duration can meet the needs of the personnel evacuation from the fire metro station. Basing on the analysis of variation of the smoke flows and the temperature, the metro station project is reasonable.
Basing on FLAC3D (Fast Lagrangian Analysis of Continua), the shield tunnel construction process is simulated, and the influence factors and their interaction for modeling are analyzed. Firstly, combing the influence factors on the reciprocity of the shield precursor with the rock-soil mass, the excavation process is simulated; at the same times, the tunnel ground subsidence and the tunnel upper vertical stress are calculated. Secondly, by mean of removing one of the factors from the stimulating model respectively, the parameters corresponding with them are also calculated. Finally, basing on Fast Fourier Transform, the ground subsidence and the vertical stress are analyzed by comparison, and the influence effects for modeling of all kinds of the factors are found out. Experimental results show that, on one hand, the influence effects to the ground settlement are more than to the vertical pressure of the tunnel; on the other hand, the factors to the simulation results include the soil-rock stress of the excavation workface causing by the shield boost, the temporary low support strength causing by the grouting at the end of the shield delaying the shield tunnel segment assembled and the soil-rock torsion force of the excavation workface causing by the shield cutterhead running.
Mine ventilation system is a repairable system, with the characters of time-varied and randomness. It made us encounter some difficulties when we discussed the system failure evolution process and its operational reliability, as well as when we sought the system reliability parameters developing trends following with ventilation system operation time variation and air adjustment. Firstly, according to the reliability theory, the failure process characteristic values, which affect the ventilation system, were defined. And then, by mean of the analysis of the failure process deterioration of mine ventilation system, the deterioration and its amelioration discriminants are given basing on two parameters’ Weibull process. Finally, on the basis of adaptive neural network technology, the ventilation system failure processes were simulated, the failure process characteristic parameters were determined, and the failure curves were drawn accordingly. The results show that the failure process of the experiment mine ventilation system is a Non-homogeneous Poisson Process; the mean time between failures of the ventilation system is between 160h and 170h; the failure ratio curves present the trends of concave or convex variation when the system failure process deterioration or amelioration.
Focusing on the road-railway level-crossings of the urban, basing on the attribute mathematics methods, the access safety influence factors of the railway level-crossings are analyzed. Basing on the analytic hierarchy process method, the assessment indexes, which impair the level-crossings system safety status, are set. Firstly, the attribute measurements of every single-index are calculated by mean of the construction of attribute measurement functions. Secondly, according to the similarity function theory, the similarity weights of the influence factors are defined, so as to assess the multi-indexes measurements objectively. Finally, make use of the confidence criterion to recognize the level-crossing system safety. Taking one of the railway level-crossings in Dalian as an example, the assessment results show that the attribute recognition result would not be affected by the index weight, namely, the weight values of the assessing indexes are considered as the same. The study shows that the method is feasible, reliable and easy for the synthetic safety assessment of the urban railway level-crossings safety
According to the techniques of the mashing and the Gaussian plume modeling, combining all kinds of the factors variation, such as the tanks leak velocity, the leak height, the wind direction and speed, and the environmental stabilization grade, the concentration distributing rules of the toxic gas continuous diffusion in the tank farm are simulated. Firstly, focusing on the central of the tank farm in chemical industrial park, mashes the tank farm as the research units for quantitative analysis and superposition calculation. Secondly, constructs the diffusion concentration distributing model of the toxic gas leak based on the Gaussian plume theory. Finally, by the condition of the single-leak hazard installation and the multiple-leak major hazard installations, the toxic gas continuous diffusion algorithms are studied, viz. in accordance with any of the influence factors variation, carve up the time sections, and then basing on Matlab technique, integrating the concentration superposition effects, simulate the concentrated distribution process of the noxious substance during the influence fields. Taking ammonia gas tank farm leakage as example, the simulation results show that the method may provide technological support for major hazard prevention and control in chemical industry park.
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